新型隧道端头扩建结构施工可靠性分析
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摘要
为了解新型隧道扩建加固结构的可靠性,通过使用有限元分析软件对新型隧道扩建结构进行数值分析并得到积极冻结40d后的温度分布云图及等温线图。通过在模型上设置3条观察路径及测温点,观察经过40d的积极冻结后,隧道周围的温度变化规律以及冻土帷幕的发展情况,得出以下结论:通过监测发现,冻结管的有效冻结半径为1m,在冻结管半径2m范围内土层受冻结管影响较大而超过2m范围的土层受冻结管的影响较小,是冻结的薄弱层。同时,冻土在初始冻结10d时间内,降温速度较快,而在冻结后期,降温速度变慢,最终降温速度趋近于0.2℃/d,冻土帷幕的发展可以将待扩建隧道完全包络,从而保证隧道扩建施工过程的可靠性,但由于冻结管的弓高较大,距离隧道较远,此处的冻结效果不尽如人意,因此提出优化方案并在此基础上进一步进行数值分析,最终得到的优化前后冻结效果表明,在对薄弱层进行加固后,冻结40d后加固结构可以完全将隧道附近土层包裹,形成可靠的加固结构。
In order to understand the reliability of the new tunnel expansion and reinforcement structure,the finite element analysis software is used to numerically analyze the new tunnel expansion structure and obtain the temperature distribution cloud map and isotherm map after 40 days of active freezing.By setting 3 observation paths and temperature measurement points on the model,the temperature change law around the tunnel and the development of the frozen soil curtain are observed after40 days of active freezing,and the following conclusions are drawn:through monitoring it is found that the effective freezing radius is 1 m.The soil layer is affected by the freezing tube within the 2 mradius of the freezing tube,and the weak layer falls beyond the 2 mrange where is less affected by the freezing tube.At the same time,the frozen soil has a faster cooling rate during the initial freezing period of 10 days,and in the late stage of freezing,the cooling rate becomes slower,and the final cooling rate approaches 0.2°C/d.The development of the frozen soil curtain can completely envelop the tunnel to be expanded so as to ensure the reliability of the tunnel expansion process.However,the arch height of the freezing pipe is relatively large and far from the tunnel,where the freezing effect is not satisfactory,therefore the optimization scheme is proposed and numerical analysis is further carried out.The frozen effect before and after optimization show that,after the weak layer is strengthened and after 40 days of freezing,the reinforcement structure can completely wrap the soil close to the tunnel to form a reliable reinforcement structure.
In order to understand the reliability of the new tunnel expansion and reinforcement structure,the finite element analysis software is used to numerically analyze the new tunnel expansion structure and obtain the temperature distribution cloud map and isotherm map after 40 days of active freezing.By setting 3 observation paths and temperature measurement points on the model,the temperature change law around the tunnel and the development of the frozen soil curtain are observed after40 days of active freezing,and the following conclusions are drawn:through monitoring it is found that the effective freezing radius is 1 m.The soil layer is affected by the freezing tube within the 2 mradius of the freezing tube,and the weak layer falls beyond the 2 mrange where is less affected by the freezing tube.At the same time,the frozen soil has a faster cooling rate during the initial freezing period of 10 days,and in the late stage of freezing,the cooling rate becomes slower,and the final cooling rate approaches 0.2°C/d.The development of the frozen soil curtain can completely envelop the tunnel to be expanded so as to ensure the reliability of the tunnel expansion process.However,the arch height of the freezing pipe is relatively large and far from the tunnel,where the freezing effect is not satisfactory,therefore the optimization scheme is proposed and numerical analysis is further carried out.The frozen effect before and after optimization show that,after the weak layer is strengthened and after 40 days of freezing,the reinforcement structure can completely wrap the soil close to the tunnel to form a reliable reinforcement structure.
引文
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[13]胡俊,杨平.大直径杯型冻土壁温度场数值分析[J].岩土力学,2015,36(2):523-531.
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[17]胡俊,卫宏,刘勇.冻土帷幕设置加热限位管时温度场数值分析[J].隧道建设,2016,36(6):688-694.
[2]仇文革.地下工程近接施工力学原理与对策[D].成都:西南交通大学,2003.
[3]黄斌,尹平,曾宪营破碎围岩小间距隧道施工响应模拟分析[J].中外公路,2012,(4):244-247.
[4]冉弥,薛博,黄瑞.既有九家湾隧道扩建方案比选研究[J].黑龙江交通科技,2018,(5):138-139+141.
[5]胡俊.一种城市地下隧道扩建环形冻结加固结构:中国,201521095975.3[P].2016-05-25.
[6]钱磊.软弱围岩隧道扩建施工过程分析[D].沈阳:沈阳工业大学,2018.
[7]贾剑,石景山,周顺华,韦凯.盾构隧道扩建地铁车站地表沉降预测及分析[J].岩石力学与工程学报,2013,32(S1):2883-2890.
[8]高干,刘元雪,徐光伟,李秀地.隧道扩建爆破震动控制研究[J].地下空间与工程学报,2010,(6):1285-1293.
[9]林从谋,张在晨,郑强,郑宏利,李明.小净距隧道原位二扩四CD工法软弱围岩稳定性及支护参数研究[J].土木工程学报,2013,46(7):124-132.
[10]朱根桥,林志,朱育才,杨成.隧道原位扩建对邻近建筑物影响评估的研究[J].岩土力学,2012,33(S2):251-256.
[11]胡俊,唐益群,张皖湘.水泥改良前后土体热物理参数试验研究[J].地下空间与工程学报,2016,12(5):1198-1204.
[12]Jun Hu,Yong Liu,Hong Wei,Kai Yao,Wei Wang.Finite-element analysis of the heat transfer of the horizontal groundfreezing method in shield-driven tunneling[J].International Journal of Geomechanics,ASCE,2017,17(10).
[13]胡俊,杨平.大直径杯型冻土壁温度场数值分析[J].岩土力学,2015,36(2):523-531.
[14]吴雨薇,胡俊,王志鑫,曾东灵,汪树成.水下清淤人工冻结板温度场数值分析[J].煤田地质与勘探,2018,(9):1-10.
[15]吴雨薇,李春芳,胡俊,王志鑫,汪树成.新型管幕冻结法温度场影响参数分析[J].煤田地质与勘探,2018,(9):1-6.
[16]胡俊,唐益群,张皖湘.水泥改良前后土体热物理参数试验研究[J].地下空间与工程学报,2016,12(5):1198-1204.
[17]胡俊,卫宏,刘勇.冻土帷幕设置加热限位管时温度场数值分析[J].隧道建设,2016,36(6):688-694.
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